The primary goal of this research is to assess the effects of housing on low- and moderate-income families with children using a population-based, econometrically-oriented approach. Our specific aims are to test: (1) how housing, assessed by crowding, physical quality (noise, health & safety, services & systems) and affordability, affects family processes (stability, stress & support) central to children's development; (2) how housing directly affects children's behavior problems (internalizing & externalizing), self-regulation (executive function & effortful control), and cognitive achievement (3) how housing indirectly affects children's development through its more proximal effects on family processes; and (4) how housing effects vary for Black, White, and Latino families. Data will be drawn from a new 3-wave longitudinal survey of ~2,654 families (w/~3,450 children 3 to 8 years old at inception) living in Dallas, Denver, Seattle and Cleveland. At each site, families wil be drawn from a waiting list maintained by the local public housing authority. All sites use a lottery to issue housing vouchers to income-eligible families that are worth ~$8,000 and that families can use to upgrade their housing. At each site, we will randomly select 166 families who win the lottery and another 166 families from the lottery losers. The lottery creates experimental variation in crowding, quality and affordability whose impacts we will assess. We also propose drawing a representative sample of the general population of each site, weighted towards the lower end of the income distribution (n=332). The MacArthur Foundation is funding collection of neighborhood and preschool/school data, and housing measures as reported by parents and as assessed by interviewers. MacArthur and a funded NICHD grant are supporting collection of a large battery of child and adult outcomes using parent reports, direct assessments, and interviewer observations. The primary aim of this application is to add to this battery assessments of (1) family processes through parent reports, Q-set methods, daily diaries, and interviewer observations; (2) objective noise levels, an important and innovative measure of housing quality potentially influential for family life; and (3) measures of children's self-regulation, a key intermediate outcome associated with environmental stressors and long-term adult outcomes. The proposed research provides a unique opportunity to identify how housing contributes to child and family well- being in ways that are not possible with extant studies. Unique study strengths include: experimental and non- experimental estimates of housing effects on family processes and child development, providing opportunity to replicate findings across experimental sample of eligible voucher investigators and broader, representative city sample that naturally varies in housing conditions; new housing measures relevant for understanding child and family well-being embedded within a well-grounded conceptual framework; multi-context design to account for other housing-related contexts, especially family, neighborhood and preschool/school; longitudinal and multi-method measures of key processes and outcomes; and racial/ethnically diverse sample of families.